The Biostatistics Core is designed to (i) provide a wide array of diverse biostatistical methods and approaches to CFAR investigators, (ii) educate CFAR investigators in the proper use of these technologies, and (iii) conduct cutting edge methodological research germane to the field. In the budget period, the Biostatistics Core has supported 45 independently funded HIV research projects, contributed to over 100 manuscripts, abstracts and presentations, generating over $250,000 of user chargebacks. The Specific Aims of the Biostatistics Core are: 1. To provide general statistical services including those involving study design, power analysis, data analysis, consultation on interpretation of results and aid investigators in writing up their results. 2. To develop and manage AIDS-related research databases for CFAR investigators and assist in utilizing these databases to address research questions. 3. To provide training to CFAR investigators in the areas of research design and analysis, epidemiologic methods and bioinformatics. 4. To synergize with CFAR programmatic areas and other Cores to interweave the Biostatistics Core services into those areas, and to utilize the scientific expertise of the Core to meet programmatic aims. 5. To interact across CFARs nationwide to facilitate interchange of research ideas to foster new directions The 'Value added" contributions of the Biostatistics Core to the CFAR Mission are the availability of resources and expertise in the design and analysis of studies ranging from basic science to comparative clinical trials. The CFAR Biostatistics Core is essential to provide access to expertise necessary for the special challenges to research in the prevention, treatment and evaluation of risk factors for HIV/AIDS.